It's election day in Britain when we meet. "Have you voted yet?" I ask Ridley Scott, as we settle down to talk in a Beverly Hills hotel suite. "I'm going to miss it, I guess," he says. "God, I hope they know what they're doing – because we don't really know who they are, these new boys, do we? You used to have to have fought in a war to be President of the United States or Prime Minister of England."

Scott, a director whose name has become synonymous with quality action movies whose heroes do battle in hostile, unfamiliar worlds, pauses for a second, as if the thought has given him the inspiration for a movie. He hits on an idea and our chat suddenly shifts towards a discussion of Winston Churchill, but it quickly becomes clear that a Scott biopic about the war leader would not dwell on the minutae of his political career. "He was in the last-ever sabre charge at Sebastopol, married, had kids, became a journalist and then a politician. He'd already designed his career at 25, 26. He runs the country in wartime, gets voted out – then comes back for another five years. Now there's a geezer!"

Actually, the sabre charge was at Omdurman in 1898, but that's hardly the sort of detail to trouble such a driven director – a man who, like Churchill, figured out early what he wanted to do, then set about doing it. Now 72, and a lean figure in jeans, blue shirt and a goatee veering into white, Scott still looks surprisingly boyish. It's hard to believe that three decades have elapsed since he reordered our understanding of sci-fi with Alien and Blade Runner, movies that put ideas on a par with action: their protagonists may do thrilling battle with space monsters and androids, but the larger villain, come the end, is invariably the beast within man.

Scott had knee surgery recently. As we turn to the subject of Robin Hood, his new movie that tomorrow opens the Cannes film festival, he pulls his chair closer and, with a little effort, settles his limb gently on a foot-stool between us, his highly polished leather boot chiming with his reputation as a director who knows that, when it comes to creating worlds, it's all about the sheen. Somewhat surprisingly, he says there's not a lot of difference between recreating the world of Robin Hood (England, 1199) and that of Blade Runner (LA, 2019), not least because the historical record on the former is so patchy, you have to use your imagination to put flesh on the bones.

"When you look at the early ballads and writings that mention Robin Hood, of which there are masses, they mostly start around the 13th century, but seem to refer to a guy about 200 years prior to then, a man who believed it was right for people to turn against their oppressors, their social superiors, because of starvation and too much tax. Times like those always throw up someone. There has to have been someone real to have left so many traces."

Robin Hood is Scott's fifth pairing with Russell Crowe. It centres on the origins of the man who, according to legend, did his good deeds dressed in Lincoln green – although, ever the revisionist, Scott has mischievously dropped that particular hue from his movie. His hero is a landless yeoman-bowman, returning from the Crusades having witnessed the death in battle of Richard the Lionheart.

Robin Hood is not a character who has been overlooked by the big screen, or the small. Scott's favourite Robin is Cary Elwes in the Mel Brooks romp Robin Hood: Men in Tights. "But I didn't really go for the fella in the green tights and the funny little feather in his cap," he says. "I was so engrossed in finding a convincing story for where he came from, how he came about, how I could justify the Sheriff of Nottingham, how King John inherited a terrible position – by the time we got through all that, we were already doing a making-of kind of film, the making of this person who later will be called a legend."

Crowe came onboard early, and his ideas on Hood coincided with Scott's. This was fortunate: according to a new book by Nicole LaPorte, Crowe apparently so hated Gladiator's climactic line – "And I will have my vengeance, in this life or the next" – that he improvised an alternative. Finally persuaded to go back to the script, he told Scott: "I'm the greatest actor in the world and I can make even shit sound good."

Scott says: "I'm a morning person and Russell's less of a morning person. But you've still got to walk in through that trailer door at 6.45 in the morning and have that in-depth discussion immediately. What I like about Russell is that he and I like to keep people honest. We're always challenging things, which can easily be misread as being grumpy. But I'm not grumpy and neither is Russell. He's got a great sense of humour – he's fun. But as I say, you'd better be on your toes!"

Scott was born in South Shields, Tyne and Wear, but spent his schooldays in postwar northern Germany, his father being an official with the Allied Control Council, which oversaw the defeated powers. Ridley went to a school for expat kids, housed in a former U-boat barracks. "I walked to school past 100 U-boats every morning," he says. "They were still cocooned in plastic because they didn't know what to do with them." It sounds like a scene from one of his movies.

He remembers, too, the US supermarket on the military base. "I fuckin' loved that place: polished apples, gleaming fruit, bananas. We hadn't seen that in England for years. Three smells always remind me of America: Juicy Fruit gum, Coca-Cola, and raspberry milkshakes. They defined that time. And then it was back to Stockton-on-Tees for the next 13 years!"

'Too pretty, too arty, too gauzy'

Living in Germany meant Scott dodged the 11-plus exam, which decided the secondary schools – and thereby the futures – of an entire generation. "I'd never have passed it," he says. His father's promotions let the family bypass many of the class strictures that might have constrained them. Scott found himself at the Royal College of Art, studying design, then went on the BBC, where he directed episodes of Z-Cars. "The BBC didn't pay very well in the 60s. You could look at your pay stubs and know exactly where you were going to be 40 years hence. So I did a commercial and it paid me so much I thought, 'I'm going to do this for a living.' I had my own company by the time I was 27 or 28: Ridley Scott Associates."

What followed were his years as Britain's foremost ad director – and, through his firm, the employer of all his rivals for the title (Alan Parker, Adrian Lyne, Hugh Hudson, and his little brother Tony, who would go on to direct Top Gun). He was always sure where he was headed, though: to movies. At Cannes in 1977, he won best debut film for The Duellists, about two feuding French officers in the Napoleonic wars. With this honour came an unsettling discovery: movies, unlike commercials, came with critics attached.

"I remember finishing The Duellists and thinking, 'That was easy.' Then I got to Cannes and thought, 'Oh, we're the English entry.' And then, 'Oh, we're gonna win!' Then the critiques came in, 'Too pretty, too arty, too gauzy.' I took that to heart because I'd always done that in commercials. Later, I realised I was just very lucky to have a good eye."

Today, 33 years on, with houses in LA, Hampstead and Provence, he makes films that, give or take the odd dip, are acclaimed and certainly varied: from Thelma and Louise to Gladiator to American Gangster, they span the decades, hitting the populist button while retaining a sort of classy machismo – more high gloss than highbrow. He has become a kind of brand, albeit a weirdly elusive one.

Indeed, with Ridley Scott Associates and his brother's Scott Free Productions now working in tandem, Scott has his fingerprints on, he estimates, 14 projects this year alone, including TV shows, and movies like The A-Team, Unstoppable and Cracks; he's also developing several projects, ranging from a US version of Red Riding to a remake of Joseph Losey's 1963 movie The Servant.

"I'm sorry for people who never knew what they wanted to be," he says as we prepare to part. "There aren't many of us lucky enough to know – but I'm one of them."

Earthquakes, equity and empire: the best films at Cannes this year

Wall Street: Money Never Sleeps

Oliver Stone's sequel, of sorts, to his totemic 1987 greed-is-good movie. It's set in 2008, on the eve of the stock-market meltdown: Gordon Gekko, played once again by Michael Douglas (right), is just out of jail.

Tamara Drewe

Posy Simmonds's cartoon version of Far from the Madding Crowd is now in movie form, with Gemma Arterton as the writer who turns up in a rural village and gets the locals hot and bothered.

Draquila

This documentary attack on Silvio Berlusconi's handling of the L'Aquila earthquake by Italian satirist Sabina Guzzanti has already raised hackles in her country's government.

Route Irish

Set in Liverpool, Ken Loach's Iraq war drama scrutinises the aftermath for a former mercenary. It's scripted by Loach's regular partner Paul Laverty, so expect tough talking.

All Good Children

Alicia Duffy is the latest in a short but significant list of British women film-makers who have followed an award-winning short with a full Cannes debut.

Over Your Cities Grass Will Grow

Sophie Fiennes's film about the unique 85-acre installation with which German artist Anselm Kiefer replaced his studio in Barjac, southern France.

The African Queen

The jewel among Cannes' archive projects: the world premiere of the restored print of the Bogart-Hepburn classic.

Hors La Loi

Director Rachid Bouchareb follows his film Days of Glory with what promises to be an even more direct attack on France's treatment of Algeria, set in 1950s Paris: one of the most hotly anticipated films for the local audience.

You Will Meet a Tall Dark Stranger

Woody Allen returns to the Croisette with his fourth film shot in London: Naomi Watts, Josh Brolin and Anthony Hopkins are all on board.

Shit Year

In a thin period for US independents, Cam Archer's arrestingly titled film will be carrying their hopes. Ellen Barkin stars as an actor who discovers that life outside the Hollywood goldfish bowl is just as tricky.

It's not an auteur smackdown à la last year, but it is still a 'Premier League' lineup, with Ridley Scott's Robin Hood kicking off 10 days of provocative films from all over. Xan Brooks and Peter Bradshaw preview the 63rd Cannes film festival